1. Field of the Invention
The present invention relates to liquid crystal display apparatuses and liquid crystal panels. In particular, the present invention relates to a liquid crystal display apparatus that uses a reflection polarizing plate as a polarizing plate, and in which light transmitted through the polarizing plate is incident on a pixel region of a liquid crystal panel to display an image. Also, the present invention relates to the liquid crystal panel used in the above-mentioned liquid crystal display apparatus.
2. Description of the Related Art
A liquid crystal display apparatus includes a liquid crystal panel in which a liquid crystal layer is sealed between a pair of substrates. The liquid crystal display apparatus displays an image on the liquid crystal panel in a pixel region where pixels are provided. For example, with a transmission liquid crystal panel, polarizing plates are arranged on both sides of the liquid crystal panel. The liquid crystal panel modulates light transmitted through one of the polarizing plates, and the modulated light is emitted to the other of the polarizing plates. Accordingly, an image is displayed.
The above-mentioned liquid crystal panel is, for example, active matrix type, which includes a TFT array substrate in which a thin film transistor (TFT) functioning as a pixel switching element is formed in a pixel region, and a counter substrate arranged to face the TFT array substrate with a gap interposed therebetween.
In the liquid crystal panel, the TFT array substrate and the counter substrate are bonded together by a seal member in a peripheral region. The gap between the TFT array substrate and the counter substrate is filled with liquid crystal, and hence, the liquid crystal layer is provided.
In the liquid crystal panel, if ionic impurity is mixed into the liquid crystal layer, image quality of a displayed image may be deteriorated. For example, the ionic impurity may be mixed into the liquid crystal layer when being eluted from the seal member. As the ionic impurity is dispersed into or aggregated in the liquid crystal layer, a display property of the liquid crystal panel may be deteriorated. In particular, when a thermosetting material, not a photo-curable material, is used to form the seal member, such a problem may be promoted by outgas generated by heat curing. To reduce occurrence of such a problem, various methods have been suggested.
For example, a method is suggested in which a peripheral electrode is provided in the peripheral region located at the periphery of the pixel region. The peripheral electrode is formed to surround the periphery of the pixel region in a frame-like form. With the peripheral electrode, a voltage is applied to the liquid crystal layer located in the peripheral region. Accordingly, impurity ions contained in the liquid crystal layer electrically adhere to the peripheral region. This can prevent the impurity ions from being dispersed into the pixel region (For example, see Japanese Unexamined Patent Application Publication Nos. 2000-338510 and 2002-196355).
In the TFT array substrate of the liquid crystal panel, a light-shielding portion is formed in the peripheral region so as to shield incident light thereon through the liquid crystal layer. A light-shielding layer is formed to surround the periphery of the pixel region in a frame-like form, and the light-shielding layer shields incident light on a peripheral circuit formed in the peripheral region by reflecting the light (for example, see Japanese Unexamined Patent Application Publication Nos. 2001-91941 and 2003-27748).
Meanwhile, in the above-mentioned liquid crystal display apparatus, the liquid crystal projector displays an image by irradiating the pixel region of the liquid crystal panel with light, and projecting light transmitted through the pixel region on a screen by a projection lens.
For example, in a three-plate liquid crystal projector that displays a color image, white light emitted from a light source is divided into light beams of three primary colors with a dichroic mirror. Then, three pixel regions of three liquid crystal panels are respectively irradiated with the divided light beams of the three primary colors. The light beams of the three primary colors are respectively modulated in the pixel regions of the three liquid crystal panels. The light beams modulated in the three pixel regions of the three liquid crystal panels are combined by a dichroic prism, and the combined light beams are emitted to the projection lens. Then, the projection lens projects the combined light beams in an enlarged manner, thereby displaying an image. That is, the liquid crystal panel functions as a light valve.
In such a liquid crystal display apparatus, a light intensity of light for irradiation of the liquid crystal panel is increased, to increase display quality of a displayed image. In particular, since the above-mentioned liquid crystal projector projects and displays an image in an enlarged manner, the light intensity for irradiation of the liquid crystal panel is markedly increased. Thus, the liquid crystal display apparatus employs members having light resistance and heat resistance.
For example, the polarizing plate employs a reflection polarizing plate which uses a light-reflective material, such as a metal lattice (for example, see Japanese Unexamined Patent Application Publication No. 2003-202558).
From among the incident light, the reflection polarizing plate transmits polarized light with a polarized component to be transmitted through the liquid crystal panel while reflecting polarized light with a polarized component except the polarized component to be transmitted through the liquid crystal panel. The reflection polarizing plate is formed, for example, by processing a metal film into a fine lattice-like form. Therefore, the reflection polarizing plate has good light resistance and good heat resistance.